Study On Infrared Spectrum Analysis And Elements Determination For Beans

There are various kinds of beans which are grown in different soil types in different regions in China. The identification of the beans species, chemical components and trace element analysis can help for a further study on the nutritional value and dietary function.FTIR spectroscopy, two-dimensional correlation infrared(2D-IR) spectroscopy and ICP-MS combined with statistical analysis were used to study the chemical components content, nutritional value and mineral elements of the different kinds of beans from different regions. The beans samples include soy bean and black soya bean in genus soybeans, broad bean and garden pea in vicia of Viceae, white kidney bean, light speckled kidney bean, black kidney bean, common bean, purple speckled kidney bean and red bean in phaseolus of phaseoleae and mung bean, adzuki bean in vigna savi of phaseoleae. The results show that the infrared spectra of the beans are similar and mainly made up of the absorbption bands of protein, lipid and polysaccharides. There were some obvious differences among their second derivative spectra in the range of 1800~800 cm-1. Correlation analysis, principal component analysis(PCA) and hierarchical cluster analysis(HCA) were performed on the second derivative infrared spectra in this region. The correlation coefficients were from 0.846 to 0.967, PCA yields classification accuracy of 97.1%, HCA provides about 97.2% of correct classification. The results of the PCA and HCA were consistent with the correlation analysis.The amide I band(1700~1600 cm-1) in the original spectra was used for decomposition and curve fitting to evaluate the contents of secondary structure of proteins. The results showed the amide Ⅰband comprises nine sub-bands in the infrared spectra of beans.The ratios of relative areas were dissimilar in different kinds of beans. It is proved that the secondary structures of protein are different in the beans. 2D-IR spectral results show the differences in the position, number and intensity of the auto peaks in the range of 860~1250 cm-1 and 1400~1700 cm-1 in the spectra of different kinds of beans.ICP-MS test results show that the P, Zn, Fe, Mn, Mg, Ca, Cu, Na and K were found in the beans. Among the mineral elements, the contents of the P、Mg、K were significantly higher than others.The content of P was the highest and the contents of elements were dissimilar in different species of beans. Compared with the vicia, phaseolus and vigna, the content of mineral elements in the soybean is much abundant. The correlation in the three macroelements(P、Mg、K) is familiar than the six trace elements(Zn、Fe、Mn、Ca、Cu、Na) of beans.The results show that FTIR、2D-IR combined with ICP-MS can provide a simple and reliable method for the chemical information, nutritious component and the mineral analysis of different type of beans.